Fig. 3.

Dorso-ventral patterning in the foregut during tracheo-oesophageal separation. (A–Z) Immunohistochemistry for the respiratory marker Nkx2.1, except for (K–N) which show in situ hybridisation for Sox2, and (T) which is stained with respiratory-specific Periodic Acid Schiff. Transverse sections are from embryos at E10.5 (A–F), E11.5 (G–S) and E12.5 (T–Z), at levels indicated by the schematic representations. Red dotted lines on schematics define the levels for measuring foregut lengths as in Fig. 2. Arrow in (R) points to oesophagus, arrowhead in (S) points to fistula, and all other arrowheads indicate dorso-ventral expression boundaries. Abbreviations: Br, bronchus; Fi, fistula; Fo, foregut; Lb, lung bud; Lt, laryngotracheal groove; Oe, oesophagus; Oet, oesophagotrachea; Th, thyroid; Tr, trachea. Scale bar (in Z): 125 μm in A–Q; 80 μm in R,S; 100 μm in T–Z.